The human need to migrate in the early days of history brought about the need to find solutions for water and liquid transportation that was to be both convenient and safe. The solution was to carry water in bags made of animal hide, known as waterskins, on journeys, as it was inconvenient to carry around clay jugs or other rigid vessels.
In the beginning of the 20th century however it was more customary to use rigid metal vessels for the transport of liquids, such as the tin water flask, gasoline jerricans, buckets and barrels.
As plastic products started to appear, around the middle of this century, it took over from metal and became widely in use in the manufacturing of rigid liquid vessels.
Furthermore as plastic production techniques evolved improved flexible liquid vessels were introduced. Examples are infusion or blood bags used in hospitals, milk bags and ketchup or mustard bags used in fast food restaurants.
Major advantages of the flexible liquid containers over the rigid ones are their relatively easy storage, as they take up almost only as much space as needed for their contents, and take very little space when empty. Another advantage of flexible containers over rigid ones is the convenience in transporting and in carrying them around. They conform to the shape of the body or vehicle which carries them. They integrate very well with other equipment carried in activities such as military and outdoor activities. Yet another advantage is the fact that rigid containers, when not filled to their maximum capacity with liquid, have excess air locked inside, which can cause oxidation of the stored liquid, whereas in flexible containers the volume of the container can be determined by the volume of the liquid inside, and therefore no (or little) air remains locked inside. Another advantage is that flexible containers are easily produced in various shapes and sizes, and their production cost is relatively low--this is true both for the production materials and the production tools. These advantages are especially valuable for military purposes or recreational purposes like jogging, cycling, mountaineering, camping etc.
In U.S. Pat. No. 4,526,298 (Boxer et al.) a sport hydration system was introduced, including a flexible liquid container or bag, suspended from the shoulder.
In U.S. Pat. No. 5,085,349 (Fawcett) a resilient valve and dispensing system for bicyclists was disclosed. The valve was designed of an elastic material and had a cut at its top edge. In order to drink the user was to bite the valve thus forcing the cut on the valve open, and allowing for the liquid to flow through.
However flexible liquid containers have a disadvantage being vulnerable and easy to pierce or burst. This has led to solutions which seek to provide external means of defense to flexible bags.
In U.S. Pat. No. 4,623,075 (Riley) a Bag-in Box type of container for pressurized liquid was disclosed, consisting of a flexible bag located inside a tube of rigid or inelastic material or a sleeve of elastic material.
In U.S. Pat. No. 4,955,512 (Sharples) a liquid container and dispenser for controlled liquid dispensation was disclosed, having a rigid or semi-rigid housing and an inner flexible bag.
In U.S. Pat. No. 4,984,713 (Chambers et al.) a carbonated beverage dispenser was disclosed, comprising a collapsible fluid holding container, disposed within an outer rigid container.
The above solutions failed to provide a flexible liquid container that is both flexible (i.e. its external walls are flexible too) and can withstand high pressures.
It is an object of the present invention is to provide a flexible liquid container which is capable of withstanding high pressures, resulting from a sudden outside impact or from a pressurized liquid stored inside.
Another object of the present invention is to provide such a flexible liquid container that would be suitable for convenient transporting and for safe use in various outdoor activities.
It is yet another object of the present invention to provide a flexible liquid container based on an impermeable inexpensive replaceable odorless and tasteless inner bag, inside a durable outer bag.
It is another object of the present invention to provide a "Bag-in-Bag" flexible liquid container, where the outer bag imparts high pressure and external impact durability properties to the inner bag which in itself does not possess these properties.